1. Technical Field
Apparatuses and methods consistent with the present disclosure relate to navigation systems capable of providing highly accurate location information.
2. Description of the Related Art
Personal navigation systems capable of providing highly accurate location information are sought after for various applications. For example, personal navigation system that can be used in global positioning system (GPS) denied environments or GPS-disrupted environments are sought after for military, first responder, and consumer applications. There is a need for personal navigation systems suitable for environments in which there is line-of-sight blockage (e.g., buildings, forest canopy, caves, etc.) and/or electrical interference/jamming. Also, such personal navigation systems can be used in clinical research to accurately measure motion of patients during therapy.
Conventional personal navigation systems use an inertial measurement unit (IMU), or some subset of inertial sensors, to measure changes in position and heading to track the movement of a person, ground vehicle, or air vehicle. These systems can also use digital pedometers that measure the impact strike of each foot and use an average stride length to compute distance traveled. These pedometers use small accelerometers to measure when each foot hits the ground. Many IMUs incorporate magnetometers for determining heading or direction using the Earth's magnetic field. However, these measurements are often corrupted inside buildings or structures due to the presence of magnetically interfering iron or electromagnetic fields.
US 20090326795 provides an example of a related art personal navigation system. A stride vector technique is presented for a pair of first and second objects, such as a pair of boots or shoes worn by a user and integrated with a personal navigation system for the user. Using the stride vector technique, a position vector is measured between user's two feet by using information gathered by sensors disposed on each foot.